From 1908 to 1914 he lectured at the University of Lvov, followed
by three years at the University of Moscow. After the end of World War I
he returned to the University of Warsaw and spent the rest of his career
there. During his career he
received honorary doctorates from ten universities, was elected
vice-president of the Polish Academy of Sciences, and was awarded the
scientific prize of the first degree in 1949.